Pitch adjusting mechanism for variable pitch propellers



July 25, 1944. H. H. RO'BY 2 PITCH ADJUSTING MECHANISM FOR VARIABLE PITCH PROPELLERS 7 Filed A r l so, 194g Patented July i944; z

.{om'rgo mm, mmorrica I f is 2,854,422 I PITCH ADJUSTING MECHANISM FOR VARIABLE PITCH PROPELLERS Horace H. Bob y, Wichita, Kant, asaignor to Roby Inc.. Wichita, Karla, a corporation or-Kans'as I Application am: so. Maseru No. 441,114

" 70mm. (mire-435.0 v y J invention relates to new and useful imvariable pitch propellers. Manyairpian'es have two or more variable pitch propellers.) It is desirable that the pitch ofthe blades and speed of rotation of the propellers be adiustedin orderythat they be moved inunison and ar synchronized. Also, the. pitch adjusting mechanism should be capable of operating each of the propellers separately. It is further de- 'sirable that the'control mechanism be simple in construction to eliminate as far aspossible the development of mechanical difficulties. The control must be mounted in the cockpit of the plane and in a position easily accessible to the pilot. An important object of my invention therefore I Other objects and advantages of my inventio will be apparent during the course of the following description.

In the drawing forming a part of this specification and wherein like numerals are employed to designate like parts throughout the same,

Fig. 1 is a diagrammatic view illustrating. the

manner in which the control mechanism is assoclated with two variable pitch propellers to si 7 "provements in pitch adjusting mechanism for tober 19,1940, which matured into Patent N 2,281,456 on the 28th day ofApril,v 1942. Immedlately behind the propeller is shown mechanism for the pitch of the propeller blades. Housing l2 rotatably retains the shanks of propeller blades l3 and: I4. A follower ring I, slidable but non-rotatably mounted on asleeve it which surrounds the crank shaft between-crank case II and housing It, fits within a cam member II. The c'am member iland follower ring II have a threaded connection so that rotation ofthe cam member causes the follower ring to move toward and away from housing 1'2. Con-.

vary their pitch. Movement of the follower ring in-one direction'increases the pitch of the blades and movement of the follower ring in the opposite direction'decreases the pitch of the blades.

The direction in which the follower ring moves is dependent upon the direction in which cam member ll isrotated. I A propeller and pitch changing mechanism identicaLWith the construction hereinabove described is shown at Ha.

' As shown in Fig. 1,'I have provided a manual control for simultaneously or independently adjusting the pitch of propellers iitand Ila. While the control mechanism here shown is adapted to simultaneously adjust two variable pitch pro- 1 pellers, it will be obvious that the mechanism can multaneously or independently adjust the pitch of the propeller blades,

Fig. 2 is a side elevation oi'avariableflpitch propeller, parts of the pitch changing mechanism being shown in section for clea'rness of 11- lustration, y

Fig. 3 is a top plan view of a pitchadjusting mechanism embodying my invention,

Fig. 4 is a fragmentary sectionalview taken on theline l-l of Fig. 3. 4

Fig. 5 is a fragmentary sectional view taken onthe line 5-5 of Fig.1, and

Fig. 6 is a modified form of .the pitch adjust-j ing mechanism.

In the drawing wherein, for the purpose of 11- pellers.

An essentially rectangular frame I8 is mounted behind the instrument board (not shown) of the airplane. Shafts i9 and 2|..extend transversely through the frame and rotatably support drums and 24 of difle'rent widths. An endless cable 25 lustration is shown a preferred embodiment of'.

my invention, the numeral ll designates a variable pitch propeller of the type shown in my copending application, Serial No. 361,884, flled 00- 'passesaround drum II and over the, peripheral. groovfe in pulley wheel ila. As shown in Fig. 1,

thecable. The jaws 28d and 28b of the clamp firmly grip'the cable and are fixedly attached to the periphery of'the pulley "a by engagement with a recess in the pulleys outer rim. The jaws are pressed together to Erin the cable by a bolt a and nut a; v I g When the propeller blades have a pitch substantially halfway between the maximum and minimum positions, clamping member 23 is located at a point diametrically opposite the point at which the cable leaves the pulley. The cable is tightly stretched between drum 2| and pulley II so that rotation of the drum will impart like rotation to the pulley.

A similar endless cable 25a extends from drum 22 to an identical pulley IIa associated with the other propeller IIa. Cable 25a is similarly secured to drum 22 by a staple 21 and to the pulley IIa by a-clamp 23; The cable 25a between the control frame and the pulley is likewise supported and guided by pulleys 23. v

Shaft 3| is journaled inthe frame I8 between drums 2| and 22. A pinion 32 keyedto shaft 3| meshes with gear 33 on drum 2| and gear 34 on drum'22. Shaft 3| is rotatably and longitudinally movable in the frame. At one endof the shaft is a handle 35 which is disposed in front of the instrument board in a position easily ac-' cessible to the pilot. The opposite end of the shaft is supported by a bearing 36. As shown in Fig. 4, the end of the shaft supported by bearing 35 is provided with a plurality of spaced annular grooves 3|a. Bearing 36 has a radial passage in which is screwed a removable plug 31. A spherical detent 33 is positioned below the plug within the passage and is movable against the action of a spring 33. When the shaft 3| is shifted longitudinally one of the grooves 3|a'will move into register with detent 33 and spring 33 will cause the detent to drop into the groove thereby resisting further axial movement'of the shaft.

When-shaft 3| is longitudinally shifted in the frame so that detent 33 is in the middle groove 3Ia, pinion 32 will mesh with both gear 33 and gear 34, as shown in Fig. 3. When the pinion meshes with both gears, rotation of handle 35 will effect simultaneous rotation of drums 2| and 22. As the drums rotate, endless cables 25 and 2541 will rotate both pulleys to the same degree. As the pulleys rotate, the follower rings within the cam members will move in unison to adjust the pitch of propellers II and Na to the same extent.

If, however, the rotational speed of one engine is faster than the other, the control device may be easily adjusted to synchronize the engines, by increasing the pitch of the faster running propeller or by decreasing the pitch of the slower running propeller.

Handle 35 under such conditions is moved to shift shaft 3| so that pinion 32 disengages one of the gears 33 or 34. For example, if propeller II is running faster than propeller IIa, it may be adjusted independently of propeller III: by shifting shaft 3| so that detent 38 seats in the innermost groove 3Ia at which time pinion 32 will disengage gear 34 but will mesh with gear 33. R- tation of the handle 35 now rotates drum 2| independently of drum 22 and the blades of propeller II are adjusted independently of propeller IIa.

When the pitch of propeller II has been adjusted so that both propellers are rotating at the same speed, shaft 3| is then shifted to bring pinion 32 again into mesh with both gears 33 and 34. There is no backlash torque on either of the drums 2| or-22, consequently neither of the drums will have any tendency to rotate when pinion 32 is out of mesh with the gears. The

gear 33. Rotation of handle 35 will, under these conditions, increase or decrease the pitch of propeller I Ia.

The form of the invention shown in Fig. 6 is identical with that shown in Fig. 3, except that two pinions 40 and 4| are provided in place of pinion 32. When shaft 3| is in the neutral position as in Fig. 6, pinions 40 and 4| are in mesh with gears 33 and 34 respectively. Rotation of handle 35 will simultaneously adjust the blades of both propellers II and Ila. It will be observed that the pinions are of substantially greater width than the gears; thus, if shaft 3| is shifted so that detent 33 enters the innermost groove 3Ia, pinion 40 will move out of mesh with gear 33 but pinion 4| will remain in mesh with gear 34. Rotation of handle 35 will then independently adjust the pitch of propeller Ila. Conversely,

if shaft 3| is shifted so that detent 38 enters the outermost groove 3Ia, pinion 40 will remain in mesh with gear 33 but pinion 4| will move out of mesh with gear 34. Rotation of handle 35 will then independently adjust the pitch of propeller II.

It is to be understood that the forms of the invention herewith shown and described are to be taken as preferred examples of the same and that various changes in the size, shape and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the appended claims.

Having thus described my invention, I claim:

1. In combination with a plurality of propellers of the type having rotatable elements for adjusting the pitch of their blades, a control device for frame, a gear on each of said drums, endless cables running over the drums and said pitch adjusting rotatable elements, means securing the cables to the drums and to the rotatable elements, a rotatable shaft longitudinally adjustable in said frame, a bearing supporting one end of theshaft, a plurality of spaced annular grooves in the end of the shaft extending through the bearing, a spring pressed detent in the'bearing adapted to enter the grooves as the shaft is shifted longitudinally to releasably hold the shaft in a selected adjusted position, and a pinion on the shaft engageable with all of the gears or with a selected one of the gears in different adjusted positions of the shaft.

2. In combination with a plurality of propellers of the type having rotatable elements for adjustadjusting rotatable elements, means securing the cables to the drums and to the rotatable elements, a rotatable shaft longitudinally adjustable in said frame, means for releasably holding the shaft in a plurality of adjusted positions, and a pinion on the shaft engageable with all of the gears or with a selected one of the gears in different adjusted positions of the shaft.

3. In combination with a plurality of propellers of the type having rotatable elements for adjusting the pitch of their blades, a control device for simultaneously or independently adjusting the pitch of the propellers comprising a frame, a plurality of drums rotatably mounted in the frame, a gear on each of said, drums, endless' cables running over the drums and said rotatable elements, means securing the cables to the drums and to the rotatable elements, a rotatable shaft longitudinally adjustable in said frame, and a pinion on the shaft engageable with all of the gears in one adjusted position of the shaft and independently engageable with each of said gears in other adjusted positions of the shaft.

4. In combination with a plurality of propellers of the type having rotatable elements for adjusting the pitch of their blades, 9, control device for simultaneously or independently adjusting the pitch of the propellers comprising a frame, a plurality of drums rotatably mounted in the frame, a gear on each of said drums, an endless cable running over the drums and said rotatable elements, means securing the cable to the drums and to the rotatable elements, a rotatable shaft longitudinally adjustable in said frame and a pinion on the shaft for each of the gears, all of said pinions being engageable with their respec-' tive gears in one adjusted position of the shaft and'each of said pinions being independently engageable with its respective gear in other adjusted positions of the shaft.

5. In combination with a plurality of propellers each of the type having a rotatable element for adjusting the pitch of its blades, a control device for simultaneously or independently adjusting the pitch of the propellers comprising a frame, a plurality of drums rotatably mounted in the frame, a driven member on each of said drums,

an endless cable running over the drums and said rotatable elements, means securing the cables to the drums and to the rotatable elements, a rotatable shaft longitudinally adjustable in said frame, and a drive member on the shaft engageable with all of the driven members in one adjusted position of the shaft and independently engageable with each of said driven members in other adjusted positions of the shaft.

6.- In combination with a plurality of propellers of the type having rotatable elements for adjusting the pitch of their blades, 8. control device for simultaneously or independently adjusting the pitch of the propellers comprising a frame, a plurality of drums rotatably mounted in the frame, means cooperating with the drums and rotatable elements to cause the drums to transmit motion to the rotatable elements, a gear on each of said drums, a rotatable shaft adjustably mounted in said -frame and gear means on the shaft engageable with all of the gears in one adjusted position of the shaft and independently engageable with each of said gears in other adjusted positions of the shaft.

7. In combination with a plurality of propellers of the type having rotatable elements for adjusting the pitch of their blades, a control device for simultaneously or independently adjusting the pitch oi the propellers comprising a frame, a plurality of drums rotatably mounted in the frame, means cooperating with the drums and rotatable elements to cause the drums to transmit motion to the rotatable elements, a driven mem ber on each of the drums, a rotatable shaft adjustably mounted in the frame, and drive means on the shaft engageable with all of the driven members in one adjusted position of the shaft and independently engageable with each of the driven members in other adjusted positionsof 

